Jaume Aguadé (Barcelona, 1953) was a full professor in the Department of Mathematics at the Universitat Autònoma de Barcelona for 34 years. His research has focused on algebraic topology and the homotopy theory of Lie groups. He has also been deeply committed to teaching and has authored several books that reflect his personal approach to mathematics education, including Notes on Elementary Topology, Mathematics and Modelling for Environmental Sciences, A Course in Linear Geometry, and the present volume. Now retired, he is currently working on a book on compact Lie groups, provisionally titled Groups Worth Meeting. Beyond mathematics, he has been an enthusiastic practitioner of hiking, mountaineering, and ski touring—activities that in recent years he has replaced with road cycling.